How much did Boris Johnson spend on his flat refurb and why is the money being probed?

Boris Johnson and his fiancee Carrie Symonds have faced questions over the funding of their renovations to the 11 Downing Street flat (Victoria Jones/PA)

The controversy over the refurbishment of Boris Johnson’s Downing Street flat was given fresh fuel when the UK's Electoral Commission announced there were “reasonable grounds” to suspect an offence may have occurred.

Here is a look at what the watchdog will be investigating and what the renovations row is about.